October 2011 archive

If you struggle to carve a jack-o'-lantern, you might prefer this high-tech alternative.Using the blasting power of a carbon dioxide laser cutter, graduate student Dan Schultz from MIT Media Lab accurately cut Medusa's face, designed by his wife, into a pumpkin.

The drawing was first scanned to create a digital version, where different details were assigned different depths. Using a tracing algorithm, coloured layers were then produced for each thickness and details were mapped onto each one. Coordinates were then transmitted to the laser, which moved back and forth over the rotating pumpkin to engrave the image. Greater laser intensity and a slower speed produced a deeper and brighter cut.

The process took three hours to complete, requiring half an hour to engrave each layer. Frequent cleaning was necessary, because vaporised pumpkin quickly built up on the lens

Given his lack of manual dexterity, Schultz was pleased with the result, although it wasn't perfect. Since pumpkins are round rather than cylindrical, the laser beam widens when reaching the edges and distorts details. The engraved face also appeared charred, caused by the beam burning through the fruit, leaving it with a ghoulish look in the daytime.

A ring trapped in a box seems determined to escape in this latest illusion by psychophysiologist Marcel de Heer. To create the brain trick, he created a virtual material with unique properties. The exterior surface is transparent and the interior is lined with a red and yellow pattern.

"The material is similar to a one-way mirror," says de Heer. "From one side, you can see through it. From the other side, you see a coloured pattern instead of a mirror."

As the box turns, the ring's behaviour starts to get unusual. When viewed from behind, you can see through it. But as it rotates so that it faces you, it sometimes seems to spin in the opposite direction and escape from the box.

De Heer isn't exactly sure why we experience the effect, although it's a variation of the hollow mask illusion. Since we are used to seeing convex surfaces like faces, our brain is sometimes tricked by hollow structures and they appear to bulge out. In this case, the curious material seems to confuse our brain in the same way.

Were you able to see this illusion? Do you have any ideas about why it occurs? Let us know in the comments section below.

The woman in this clip dips into a hypnotic state after hearing the word 'hypno'. During the transition, her eyes don't blink and lose focus while she is no longer motivated to do anything without being asked.

For over 100 years, researchers have debated the existence of a true hypnotic state, marked by physiological changes in the brain and resulting in behavioural changes in the body. To show that this state isn't something a person can pretend to experience, Kallio compared the unblinking stare of the woman in this video with those of 14 control subjects who were instructed to attempt to recreate the changes in pupil size, blinking rate, and fixated vision that she displayed.

"They tried to mimic the eye movements we saw during hypnosis but they weren't able to do that accurately because they were reflexes," Kallio says. "Changing your pupil size isn't something people have a skill to do."

Combining observational evidence with EEG readings, Kallio's work confirms the previously held belief that a hypnotic state results in changes to the frontal lobe of the brain, in areas that play crucial roles in attention and motivation-related behaviours, as well as in regulating eye movements.

"We found that during hypnosis, the frontal area was almost perfectly disconnected from the rest of the brain," says Kallio. "There are usually lots of connections but during hypnosis they were almost gone."

According to Kallio, this lobotomy-style lack of initiative made his research more difficult. While the subject in this video was completely capable of doing difficult tasks during hypnosis, she had to be told what to do, even down to blinking. "We had to take breaks because her eyes got really dry," he says. "She wouldn't blink unless we reminded her to do it."

Perched high up on the mountaintops of Northern Chile, the region's powerful telescopes provide unrivalled stargazing conditions for astronomers. Last month, our chief features editor, Valerie Jamieson, explored the extreme environment that is home to these observatories. You can follow her journey in this narrated slide show.

First stop: the Very Large Telescope at Paranal Observatory which is made up of a moving assembly of four giant telescopes and four domed auxiliary telescopes. Its dry and elevated location eliminates the scattering effects of water vapour, allowing this telescope to capture the first shots of an exoplanet and image some of the oldest stars in the universe.

Next, the tour travels upward to the intended location for the European Extremely Large Telescope, a gargantuan structure planned to crown a 3000-metre-high mountain. The project calls for the top of the mountain to be blown off.

A fish out of water is not as helpless as you might think. When threatened by looming predators, or evaporating puddles, some fish are able to leap many times their own body length.

Biologist Alice Gibb from Northern Arizona University and her team are now studying how fish behave on land. In the video, you can watch different species of fish propel themselves. To perform the move, a fish curls up by using muscles on one side of its body to throw its head back and shift its center of mass tail-ward. Then, muscles on the other side kick in, stabilising its back side and setting it up for flight mode.

After painstakingly arranging a bed of brass nails, physicist Stephen Morris and his graduate student T. Lynn MacDonald of the University of Toronto decided to shake things up. The result is captured in this time-lapse where the perfect crystalline arrangement appears to melt, much like the physical process of crystal liquefaction.

The shaking action is produced by a rectangular plate jostling up and down with increasing force. Buffeted by the motion, the nail bed's crystal-like structure passes through a pattern of less-ordered states. This resembles the phases that a crystal of long molecules undergoes as it heats up.

According to Morris, the parallels are surprising because the shaking only roughly equates to an increase in temperature and the different stages are not equilibrium states.

"Since the nails lose energy on collisions, we must continuously feed energy in via the shaking," Morris said. "So this is a very non-thermodynamic situation, yet we observe more or less the same phases as in liquid crystals."

His group is studying the patterns that arise as non-equilibrium systems change.

The lava contains huge quantities of super-hot steam, carbon dioxide and sulphur. When the molten rock hit the cool, dense waters of the Pacific, these gases cause explosions that fragment the new rock, creating the characteristic pillow and bubble shapes seen in the video.

If light travelling in air suddenly passes through glass or water, it bends. But the speed at which it propagates also changes. In this One-Minute Physics episode, animator Henry Reich explores why light slows down in glass or water, only to speed up again when it crosses back into air.

UPDATE: Congratulations to Adam Wanderer who won the competition for suggesting the invention of an app that hones your internal clock, allowing you to estimate the time using your own mind rather than relying on a time-keeping device. Thanks to everyone who entered - we were inspired by all the innovative submissions!

Think a ticking clock is an outdated way to depict time? Why not invent a more novel solution - and win this cool touchscreen watch, courtesy of TokyoFlash.

We want to hear your ideas for representing time using computer technology. Here's some inspiration to get your creative juices flowing.

Surely if flying saucers existed, they would float around like the disc in this video. The demonstration by physicist Boaz Almog from Tel Aviv University, Israel, at the Association of Science-Technology Centers (ASTC) Annual Conference in Baltimore, Maryland, earlier this week illustrates how a superconducting plate can be fixed in 3D space while levitating above a track of permanent magnets. But this isn't simply magnetic repulsion: the disc can also stay suspended upside down when the magnets are flipped over.

This epic time-lapse takes you on a sweeping tour of nature's dynamic beauty, capturing a
blizzard overtaking Monument Valley in Colorado and exquisite views of Yosemite National Park. Created by Henry Jun Wah Lee of Evosia
Studios, it was presented last month at the Jane
Goodall Live event in Los Angeles, where the primatologist appeared on screens to interact with a theatre audience.

Lee's film was chosen for the screening because, like Goodall, his mission is to reconnect viewers with
nature.

"We are
trying to raise awareness about the beautiful world we live in and the need to
preserve it for future generations," he says. "Just as there are species
of animals that may never again roam this planet in the next few generations,
there are beautiful landscapes and places that may not be around in twenty or
thirty years."

The opening landscape is set
in Ancient Bristlecone
Pine Forest in California, which Lee claims is the most otherworldly place his work has taken him to date.

"At
12,000 feet in the desolate mountains, the sky is so clear you feel swallowed
up by the universe," he explains. "You feel so small and insignificant against
the billions and billions of stars above you."

You've probably seen light that looks pink, but where does this colour come from? Different wavelengths of visible light correspond to colours of the rainbow - and pink isn't one of them. In our latest One-Minute Physics video, animator Henry Reich takes us through the mysterious make-up of pink light.

At first, it looks like an ordinary pattern of dots on a sheet of paper (see video above). But focus on the rolling candle in front of it and suddenly they start to do the wave. The illusion, developed by Greg Ross of Greeenpro Productions in Pennsylvania, is a variation on a trippy rotating snake pattern created by psychologist Akiyoshi Kitaoka from Ritsumeikan University.

According to psychologist Simone Gori of the University of Padua, the difference in contrast within each dot is key for the illusion to work. When the pattern is combined with eye movement as another object is tracked, a wave-like motion is perceived which always proceeds from dark regions to lighter ones.

Although the effect is known to be stronger when the pattern appears in our peripheral vision, researchers still don't know exactly why we perceive this brain trick. After viewing the rotating snake pattern for a few seconds, many viewers stop seeing the rotation once their eyes have adapted to the image.

Did the illusion work for you? Do you have any ideas about why our brain perceives the phantom motion? Let us know in the comments section below.

Want to find out which mouse is the mightiest? In this video, a face-off in a narrow tube determines who's the boss. The trial is a test for social dominance used by Hailan Hu of the Chinese Institute of Neuroscience in Shanghai and his team to investigate the neural underpinnings of this bravado.

They found that strengthening certain neural connections in the brain gave mice a confidence boost. You can read our full story about the neuroscience of mouse social hierarchy here.

If you're driving on a bridge during an earthquake, your vehicle's shock absorbers could affect the impact. In some cases, the suspension system can help dissipate potentially destructive energy, but it can also exacerbate the effect by tossing the vehicle back and forth.

Now, Ian Buckle and colleagues at the Center for Civil Engineering Earthquake Research at the University of Nevada, Reno have built a full-scale bridge in the largest earthquake simulator in the world to investigate what really happens.

The researchers loaded up real trucks on the bridge, which is set on top of four shake tables. They used data from the 1994 Northridge earthquake near Los Angeles to replicate realistic seismic motion.

Preliminary results indicate that for small earthquakes, trucks help the performance of the bridge. But the team will soon recreate earthquakes three to four times as intense as the Northridge quake to verify if the effect still holds.

Producing an annoying sound may seem like an unlikely way to attract a mate. But male and female mosquitoes buzz at each other to signal their interest, which sometimes leads to a harmonic duet (see video above).

Lauren Cator and Laura Harrington at Cornell University in Ithaca, USA decided to investigate why mosquitoes would bother harmonising. They tethered female mosquitoes to strands of human hair and released three male suitors close to each one, while capturing video and sound recordings of the encounters.

Their analysis revealed that harmonising males were much more likely to get lucky and to produce offspring. The males that couldn't sing in tune were often rejected, with females kicking them, holding them away with their legs, or even tilting their abdomens to prevent genital contact, as shown in the video.

Time travel is more than just science fiction: it could be possible according to the laws of physics. However, building a time machine would likely be difficult and require technology that doesn't currently exist. In this animation, we look at how to build a time machine and the perplexing implications of such a feat.

Neurosurgeons at the University of Pittsburgh School of Medicine in Pennsylvania implanted a grid of electrodes, about the size of a large postage stamp, on top of Hemmes's brain over an area of neurons that fire when he imagines moving his right arm. They threaded wires from the implant underneath the skin of his neck and pulled the ends out of his body near his chest.

The team then connected the implant to a computer that converts specific brainwaves into particular actions.

As shown in this video, Hemmes first practices controlling a dot on a TV screen with his mind. The dot moves right when he imagines bending his elbow. Thinking about wiggling his thumb makes the dot slide left.

With practice, Hemmes learned to move the cursor just by visualizing the motion, rather than concentrating on specific arm movements, says neurosurgeon Elizabeth Tyler-Kabara of the University of Pittsburgh in Pennsylvania, who implanted the electrodes.

After this initial training, Hemmes navigated a ball through a 3D virtual world and eventually controlled the robotic arm, all with his mind. The electrode grid was removed after the 30-day trial.

The team is now recruiting people for a trial of a more sensitive electrode grid that detects messages from individual neurons, rather than a group. They plan to implant two electrode patches, one to control arm movements and another for fine hand motion. The ultimate goal is to allow paralysed people to move individual fingers on a robotic hand.

Like a character from a retro sci-fi flick, this magnetic putty quickly swallows up strong rare-earth magnets when the process is sped up in a time-lapse. Micron-sized magnets embedded in the silicone are jumbled up when the putty is kneaded, causing them to misalign and creating a poor magnet. However, once the putty is exposed to a magnetic field, they line up again and the blob becomes magnetised.

Seattle-based internet consultant David Lindahl captured the first clip by snapping an image every 10 seconds as the putty engulfed a large stack of magnets. The other clips were filmed by Ondřej Cífka, a high school student in Prague, who arranged the putty around a powerful neodymium magnet and filmed dramatic close-ups of the action.

You can concoct your own magnetic putty by following this guide, which involves adding ferric iron oxide powder to silicone putty. Let us know in the comments section below if you come up with any interesting scenarios.

This E. coli colony creates a stunning synchronised light show using small molecules to sense and talk to one another. The phenomenon known as quorum sensing allows microbes to work together and behave more like a multicellular organism.

The colony has to reach a certain population size before its citizenry starts acting communally. A small group of bacteria first flashes almost at random. But after yielding certain numbers, they create a cascade of blue light. Adding a gene for a fluorescent protein allows the bacteria to glow in response to changing conditions. Jeff Hasty, a bioengineer at the University of California, San Diego, is using this property to develop cellular sensors that could detect pollutants and aid with drug delivery.

While teamwork is helpful for cellular sensors, fostering rebellion could protect against virulent microbes. Scientists are on the hunt for ways to exploit do-nothing microbes who reap the benefits of the community without doing the work that contributes to its survival. Some of these cheaters lack critical genes virulence. If these mutants take over, they would cause the downfall of the group. To learn more about cheatobiotics, see "Cheatobiotics: Send in the subversive superbugs".

These spinning silhouettes confound the brain with many possible interpretations. Developed by psychophysiologist Marcel de Heer, the women appear to twirl full circle at times either clockwise or counter-clockwise. At second view, they could be turning in 180 degree increments from side to side.

A variant of the spinning dancer illusion, this quartet encourages many ways of seeing. What changes when you view the women in pairs or individually? Does changing your focus from the head to the feet or hands cause your perception to shift? De Heer suggests the addition of several figures allows the viewer to see many possible rotations without diverting his eyes.

The ambiguity arises because this shape-shifting two-dimensional shadow is interpreted by the brain as a 3D image. Because the silhouettes lack depth information, the brain at first sees the figure turning one way then another. As psychologist Simone Gori of the University of Padua explains, the primary visual cortex analyses the 2D figure as if it is moving through small viewing windows. The higher visual cortex combines this information about the flat 2D motion with 3D structure information to create the sense of ambiguous 3D motion.

The degree of control you have over the image may be an illusion itself. A shift in focus may reverse the motion in your mind as de Heer contends, but you may find yourself quickly losing control. Stuart Anstis, a psychologist at the University of California, San Diego, likens the brain to a judge compelled by two opposed but equally convincing witnesses.

Human surgeons work miracles on a daily basis, but intricate operations can challenge even the most dextrous of hands. More and more, surgical robots, such as Da Vincifrom Intuitive Surgical in Sunnyvale, CA, are providing a stable assist.

In this video, a urology fellow at Southmead Hospital and the North Bristol NHS Trust in Bristol, UK, peels a grape. Using a specially designed display and teleoperation controls, he is able to see both real and virtual representations of what the robot's instruments are doing. The robot has four arms, three of which can hold instruments like a scalpel or surgical scissors. The fourth arm carries an endoscopic camera with two lenses, which gives him a stereoscopic view of the action.

The US department of defense is now looking at incorporating similar robots into "Trauma Pods" - partially automated field hospitals capable of caring for severely wounded soldiers while they wait to be evacuated. In 2009, the da Vinci system was inducted into the robot hall of fame.

Step aside film critics; this short is meant to be reviewed by apes. The unique production, called Primate Cinema: Apes as family, features an animatronic ape interacting with impersonators on camera. The split screen view shows the actual footage on the right while the chimps' response can be followed in the left panel.

Read our full review to find out how the premiere was received at the Edinburgh Zoo here.

This stink bug gulps down a hornworm like a milkshake, using a specialised straw-like mandible to vacuum up its insides, while leaving the casing intact. The bug's mandible consists of two tubes: one that digests food, before the other transports it up. About halfway through the clip, you can see it feeling around inside the worm for more grub.

The video was filmed by Christopher Hedstrom, a research assistant in the Walton Horticultural Lab at Oregon State University, who was feeding the voracious bug when he noticed the worm deflating. By perching a camera on a microscope, he was able to capture the critter downing its liquid meal and later sped up the 15 minute session in a time-lapse.

Hedstrom and his team are currently studying an invasive species of stink bugs that's expected to swarm the mid-Atlantic US this fall. Unlike the meat-eating bug in this video, brown marmorated stink bugs like to munch on apples and other crops. They're investigating whether a non-native wasp could be used to control the invasive bug's spread, by laying its own eggs inside them, but it's not yet known whether native bugs will also fall victim to the parasitic wasp.

Lurking beneath a pit of sand, this ant lion snags an ant with its gaping jaws. But, compared to other insects, its attack speed is on the slow side. By observing video footage, Eric Lambert and his team from University of South Florida in Tampa found that it took an average of 18 milliseconds to ensnare prey. However, it achieves a superprecise grip by using two mandibles to strike simultaneously.

Electrons move superfast, but thanks to this slow-mo simulation from the Max Planck Institute of Quantum Optics, we can now perceive their motion. With advances in science, however, movies of an atom's inner workings could soon become reality.

You probably wouldn't expect a ball to behave like a sound wave. But in this video, animator Henry Reich ventures into the bizarre world of quantum mechanics, where electrons and protons can flip-flop between wave and particle properties.